CAP1400 is an advanced large passive nuclear power technology under research and development, and related electromechanical equipment should be improved to guarantee the safety. The driving systems of main steam and feed water isolation valves are electromechanical equipment in nuclear power plants with nonlinear systems, which are not easy to be identified with traditional mathematical models. This article presents the design process of a novel driving system of the main steam isolation valve under the emergency quick-closing situation, which do not need the mathematical models. The novel driving system, which has a symmetrical and concise structure, is designed to include only two independent hydraulic output circuits, two independent hydraulic input circuits, and a nitrogen circuit for auxiliary driving. A cosimulation method, which takes advantage of AMESim, Adams, UG, and MATLAB, was proposed to establish the models of the main steam and feed water isolation valve and the driving system. Finally, co-simulations and experimental verifications of the emergency quick-closing situations, which include two hydraulic output circuits working together for quick closing and only one hydraulic output circuit for quick closing, were provided to confirm the performances and effectiveness of the proposed driving system and co-simulation method.

In this paper, a new procedure for implicit surface reconstruction from oriented points is presented. A normal constraints based implicit polynomials fitting method and the partition of unity approach are fused into our framework. Firstly, a large scale input data is subdivided into some overlapping patches by octree. Then the global implicit surface is transferred into local implicit patch fitting and blending of them. To fit the local implicit polynomials, we build an energy by three steps corresponding to enforcement of the interpolatory constraints, satisfying of normal constraints and enhancement of fitting stability. The unkowns in an implicit polynomial are determined by minimizing this quadratic energy function. It is demonstrated in some experiments with several real data sets that this combination provides an intuitive and effective means to approximate the scattered point data associated normals.

The driving device of the main steam and feed water isolation valves is one of the most important electromechanical equipment in nuclear power plants, and its motion performances are related to the safety of nuclear power plants. This article proposes an optimization methodology to research the motion performances. In the methodology, inputs are the motion performance indexes and the major influencing parameters with no need for complex mathematical models of the electromechanical equipment; the co-simulation model or the prototype are adopted to illustrate the influence rules of major parameters on the motion performance indexes; objective functions for optimization, which combine motion performances with weight factors, can reveal the influence rule curves. Then based on the methodology, motion performances of the equipment are analyzed and the key indexes are selected. Besides, the maximum pressure of the driving device is chosen as the major parameter and a dimensionless objective function synthesizing the motion performance indexes is proposed. Finally, the influence rule curve where the dimensionless function varies with the maximum pressure is obtained by the co-simulation and the experimental study on the prototype verifies the results, which provides references for the further research and development in the engineering application. For other electromechanical equipment, the method is an efficient tool to design, verify, and optimize the performances.

This article presents the study of the medium block effects on the driving device performances of main steam and feed water isolation valves, which are typical electromechanical equipment in nuclear power plants. The equipment simulation model is established, which can calculate motion performances under all working situations. The medium blocking force models during the motion of valves are established and the blocking effects on the driving device performances are calculated and analyzed. The simulation results show that the medium block has little effects on the opening performances of the driving device, while it has important effects on the closing performances, especially on the quick closing, which suggests that the equipment should be lubricated to reduce resistance coefficients and the main parameters of electromechanical equipment should be tuned and calibrated to guarantee the quick closing time.

Hydraulic oil is an important part of the pneumatic-hydraulic type driving device of the main steam isolation valve, whose physical property effects on the electromechanical equipment performances were never studied. This paper reports the research on the physical property effects. The effects of the environment on hydraulic oil physical properties are discussed and the plant environment are introduced. Based on the mechanic-electric-hydraulic co-simulation model of the equipment, the motion performance indexes of the driving devices are illustrated and the cycle simulation methodology is proposed. The influencing laws of hydraulic oil properties on the motion performance indexes are revealed and illustrated. The results show that hydraulic oil properties have important effects on the motion performances of the equipment. The results provide important references for designing the equipment and experimental verification, which make the equipment more reliable.